Advertisements are NOT for monetary needs. We engaged with some "Search Engine Optimization" (SEO) experts, they recommended having advertisements on website. Their techniques have shown that sites with advertisements are indexed better by search engines. So yes, they are necessary for getting deeper indexing of content on our website, so you can find what you are looking for easily via popular search engines. We rotate the advertisement providers in such a way that all search engines are indexing the content. We tried this without interfere with your elegant browsing experience. We do not place any pop-up advertisements.
We do not see online advertisement as source of income, it is mainly for technical reasons that will get content searchable.